Alpha-olefin polymers

ABSTRACT

This invention deals with viscosity improvers which are obtained through the use of a mixed catalyst system comprising a tertiary organo halide and a Lewis acid catalyst. A liquid alpha-olefin polymer composition having a polymodal distribution with peak molecular weight maximum at 2,000 to 5,000 and at 50,000 to 75,000 is useful as a lubricating oil.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention describes processes for preparing alpha-olefin polymershaving particular viscosity characteristics and which are highly usefulin gear lubricant systems.

2. Introduction to the Invention

It is known that polymerized olefinic materials may be utilized asviscosity improving agents (commonly known as viscosity improvers) toprevent base oil stocks from thinning out at high temperatures. If abase oil thins out at high temperatures then the essential lubricatingcharacteristics of the composition can be lost. Thus, a viscosityimprover is a material which at low temperatures is essentiallynon-active and at higher temperatures acts to maintain the viscosity ofthe entire fluid system as the temperature increases. It is highlydesirable that a viscosity improver be shear stable. By being shearstable, it is meant that the viscosity improver under conditions of highshear does not degrade (undergo chain scission). If the viscosityimprover is subject to high shear and chain scission, the effectivenessat high temperatures is reduced. The present invention deals withalpha-olefin polymers which are typically obtained from a binarycatalyst system and which are highly shear stable.

Fontana et al U.S. Pat. No. 2,678,957 issued May 18, 1954 describes thepolymerization of olefinic hydrocarbons. The catalyst system in theFontana patent is described as AlBrX₂ or AlBr₂ X where X is a halogenother than bromine. The foregoing catalyst is stated as being dissolvedin a non-polymerizable hydrocarbon solvent and in using a promoter. Thepromoter is RY where R is hydrogen or an alkyl group and Y is halogen.The monoalkylethylenes polymerized according to Fontana may berepresented by the formula RCH═CH₂ where R is an alkyl group. Fontanadescribes monomer materials ranging from propylene to octadecene-1.

U.S. Pat. No. 4,162,233 issued July 24, 1979 to Kramer describes amethod for obtaining hydride transfer reaction products useful inisomerization and alkylation reactions. The stated acid systems utilizedby Kramer are capable of stabilizing high concentrations of tertiarycations and further capable of forming carbonium ion salts includingboth dimeric and monomeric anions.

U.S. Pat. No. 3,436,379 issued Apr. 1, 1969 to Hambling et al describesthe copolymerization of mono-olefinically unsaturated hydrocarbons,having a slower polymerization rate than isobutene, and one or moreconjugated dienes in the presence of a Friedel-Crafts catalyst, and aminor proportion of isobutene. Furukawa et al U.S. Pat. No. 3,361,731issued Jan. 2, 1968 describes the polymerization of vinyl ethers,styrene, alpha-methyl styrene and isobutylene with a catalyst systemdescribed as an aluminum halide etherate. U.S. Pat. No. 2,488,736 issuedto Palmer on Nov. 22, 1949 describes the polymerization of olefinicmixtures in the presence of a Friedel-Crafts catalyst of enhancedactivity.

Hersberger U.S. Pat. No. 2,474,671 issued June 28, 1949 describes aprocess for the Friedel-Crafts polymerization of unsaturatedhydrocarbons to produce polymer products which are stated to be haveuniform composition and physical properties regardless of the degree ofpolymerization.

U.S. Pat. No. 2,521,431 issued to Walsh et al on Sept. 5, 1950 describesthe polymerization of olefins. Walsh teaches that Friedel-Craftscatalysts may be utilized in the presence of an alkyl halide promoterfor the polymerization reaction. Walsh states that the polymerizationreaction may be improved by the addition of controlled amounts of water.U.S. Pat. No. 2,581,154 was issued to Walsh et al on Jan. 1, 1952. ThisWalsh patent describes the polymerization of low molecular weightunsaturated hydrocarbons in the presence of a Friedel-Crafts catalyst.

Calfee et al U.S. Pat. No. 2,644,798 issued July 7, 1953 states thatolefinic polymerization processes, and in particular those usingaluminum halide catalysts, may be improved by using such catalystshaving a molar ratio of halogen to metal of less than 3 and furthercontaining oxygen in the catalyst molecules. The oxygenated aluminumhalides are stated to be dissolved in a low-freezing,non-complex-forming solvent. The solvents include such materials asmethyl chloride, ethyl chloride, or propyl chloride or other mono- orpoly-halogenated alkanes containing up to about 5 carbon atoms.

Edwards in U.S. Pat. No. 3,317,500 issued May 2, 1967 describes theproduction of hydrocarbon-insoluble elastomers obtained from4-methyl-1-pentene. The polymerization of the subject olefin by Edwardsis stated to take place in the presence of a catalyst which may be solidaluminum chloride or monoethyl aluminum chloride at temperatures atabove -20° F. (-29° C.). Various methyl halide solvents are described asbeing useful by Edwards in his process. U.S. Pat. No. 3,317,501 issuedMay 2, 1967 to Edwards contains similar disclosures.

As previously stated, it has been discovered in the present inventionthat shear stable liquid alpha-olefin polymers preferably being of abimodal distribution may be obtained through the use of a catalystsystem comprising a tertiary organo halide and a Lewis acid catalyst.

Throughout the specification and claims percentages and ratios are byweight, temperatures are in degrees Celsius and pressures are in KPagauge unless otherwise indicated. Ranges and ratios given herein areexemplary and may be combined. To the extent that the referencesdescribed herein are relevant, they are herein incorporated byreference.

SUMMARY OF THE INVENTION

The present invention describes a process for preparing an alpha-olefinpolymer comprising contacting at least one alpha-olefin with a catalystsystem comprising a tertiary organo halide and a Lewis acid catalystunder polymerization conditions thereby obtaining the alpha-olefinpolymer.

A further embodiment is a process for preparing a propylene polymercomprising contacting propylene with a catalyst system comprisingaluminum chloride and at least one tertiary lower alkyl chloride underpolymerization conditions in the presence of an activating amount ofwater and employing a halogenated solvent, thereby obtaining thepropylene polymer.

The product obtained as described above having a molecular weight of2,000 to about 100,000 is also useful in gear oils, lubricants,functional fluids and greases as further described herein.

A further aspect of the invention is an alpha-olefin polymer compositionhaving a polymodal distribution with peak molecular weight maximums at2,000 to 5,000 and at 50,000 to 75,000.

DETAILED DESCRIPTION OF THE INVENTION

The present invention deals with obtaining alpha-olefin polymers whichare particularly useful as shear stable viscosity improvers in a varietyof oil based fluids. The alpha-olefin polymers obtained herein aretypically liquids having a viscosity of less than 150,000 cps at -40° C.For instance, the liquid shear stable viscosity improvers obtained fromthe alpha-olefin polymers described herein are useful in lubricatingoils such as for internal combustion engines, functional fluids such ashydraulic oils or as a thickener for a grease composition. Thealpha-olefin polymers useful herein are as described below.

In particular, any alpha-olefin monomer may be utilized to prepare thealpha-olefin polymers. Alpha-olefin monomers are simply described by theformula RCH═CH₂. The group R is a hydrocarbyl residue comprising atleast one additional carbon atom and any other non-interferingsubstituents and molecules. It is preferred that the group R behydrocarbon based as is later described with regard to the preferablecomponents for the alpha-olefin monomer. That is, R should be at leastone carbon atom, and is preferably not an aromatic species such asstyrene, e.g., the polymer is substantially free of aromatic content.The desired monomers are normal or linear. The polymers may behomopolymers, copolymers or terpolymers.

Typically, the alpha-olefin monomers will contain from about 4 to about30 carbon atoms total. A more preferable range for the alpha-olefinmonomer is one which contains a total of about 6 to about 16 carbonatoms. As previously noted, the alpha-olefin monomers are preferablyhydrocarbon based. In particular, the alpha-olefin which contains 4carbon atoms is preferably the simplest hydrocarbon species, e.g.,1-butene. Thus, the particularly desirable alpha-olefin monomers do notcontain a second reactive vinyl group, e.g., 1,3-butadiene. It isfurther desirable that any additional unsaturation within thealpha-olefin monomer should also be minimized or eliminated. Thus, theuse of 1,3-pentadiene is preferably avoided herein. That is, theextraneous double bond in addition to that giving rise to thealpha-olefin structure may rearrange within the molecule to a moreactive species thereby giving the undesirable dialpha-olefin structure,e.g., 1,4pentadiene.

Thus overall, the preferred species in the present invention is analpha-olefin which contains a single vinyl group (olefin) at theterminus of the molecule (mono-alpha-olefin). Specific examples ofalpha-olefins which may be utilized herein are 1-butene, 1-pentene,1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene,1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene,1-heptadecene and 1-octadecene. Also useful herein are small amounts ofnon-alpha-olefins. Thus, materials such as isobutylene (CH₃)₂ C═CH₂ areuseful herein. Typically, non-alpha olefins should not be present atmore than about 10%, preferably 5% by weight of the total olefin charge.The non-alpha olefins may also be excluded from the monomer charge.

Branching in the olefin monomer away from the 1 and 2 carbon positionsis also within the scope of the present invention. While branchedalpha-olefins are not desired, they may be included at less than 10%,preferably less than 5% by weight. Branched alpha-olefins include3-methyl, 1-pentene. It is preferred herein that the alpha-olefin notcontain any tertiary carbons as these materials may be selectivelyunreactive in the process of the present invention.

Particularly useful in the present invention are mixtures ofalpha-olefins. In particular, mixtures of the normal alpha-olefins:octene and dodecene; heptene and nonene; hexene and decene; and octeneand tetradecene are useful when employed herein. Ternary mixtures suchas the normal octene, dodecene and hexadecene may be used. A furtherdesirable ternary mixture of alpha-olefins includes a mixture of thenormal octene, dodecene and tetradecene.

Where binary mixtures of two alpha-olefins are utilized, they aretypically present at from 5% to 95%, preferably 10% to 90% by weight ofeach of the alpha-olefins. Where ternary mixtures are employed, each ofthe alpha-olefins will be utilized at from about 5% to about 90%,preferably about 10% to about 70% of each of the monomers.

The catalysts employed herein are a first catalyst system comprising atertiary organo halide and a second system employing a Lewis acidcatalyst.

The tertiary organo halides with which the present invention isconcerned are of the general formula

    R.sub.1 R.sub.2 R.sub.3 CX

wherein X is a halogen and R₁, R₂ and R₃ are all hydrocarbyl groups. Thevalue of X as a halogen may be any of the typically employed halogenatoms, e.g., fluorine, chlorine, bromine or iodine. Preferably, thehalogen, X, will be chlorine or bromine and most preferably chlorine.

R₁ through R₃ may be the same or different hydrocarbyl groups, providedthat the hetero atoms within the hydrocarbyl groups are not deleteriousto the desired catalyst function described herein. It is preferred thatR₁ through R₃ are all the same and that most preferably all are alkyl.There is a further preference for herein for having R₁ through R₃ beinga straight chained or normal hydrocarbon group. It is particularlypreferred that the tertiary organo halide is a tertiary-alkyl halide. Itis further preferred that the total number of carbon atoms in thetertiary alkyl halide be from about 4 to about 12 carbon atoms.Preferred tertiary organo halides are t-butyl chloride and t-amylchloride.

The second catalyst employed in the present invention is a Lewis acidcatalyst. Simply stated, the Lewis acid catalyst is any material whichcatalyzes the desired reaction to obtain the alpha-olefin polymer andwhich is further described as a molecule or ion that can combine withanother molecule or ion by forming a covalent bond with two electronsfrom the second molecule or ion. Specific examples of Lewis acidcatalysts useful in the present invention include boron trifluoride,aluminum halides such as aluminum chloride, aluminummonochlorodibromine, aluminum bromide and aluminum monobromodichloride.

An aprotic solvent is typically utilized in practicing the process ofthe present invention. The solvent is a normally liquid material at 20°C. The solvent is also preferably a halogenated hydrocarbon. Typically,the solvent utilized herein will be methylene chloride. Other suggestedsolvents include monobromomonochloromethane, methylenebromide,1,2-dichloroethane, 1,1-dibromocyclopropane 1,1-dichlorocyclopropane,cis 1,2-dichlorocyclopropane, trans 1,2-dichlorocyclopropane, cis1,2-dibromo-cyclopropane, and trans 1,2-dibromocyclo-propane.

The solvents utilized herein are preferably geminal dichloro compoundssuch as ethylene dichloride or methylene chloride. An additionalutilizable solvent herein is carbon tetrachloride.

A further feature of the present invention is to conduct thepolymerization reaction in the presence of an activating amount of aprotic compound. Typically, the protic compound is water. The termactivating amount as later discussed means that amount which promotesthe overall polymerization reaction and is not such an amount as tosubstantially decrease the polymerization reaction or to inactivate thecatalyst system.

An activating amount of the protic compound is typically less than 1%,preferably 0.0001% to 0.1%, by weight of the catalyst system.

REACTION VESSEL

The reaction vessel utilized in preparing the polymers of the presentinvention is typically either 0.95 cm stainless steel or is a glasslined reactor. The reaction vessel is equipped with a mechanicalstirring system, reservoir for the alpha-olefin to be polymerized and afeed inlet. Temperature measuring means such as a thermometer are alsoincluded together with a condenser, a cooling jacket, and the ability tomaintain an inert atmosphere (preferably nitrogen). Alternatively, thecooling jacket for the reaction vessel may be utilized for heating thevessel during the reaction. However, as the polymerization reaction isexothermic and the general temperature conditions described herein arerelatively low, it will be more common to cool the reaction vessel thanto heat the same.

PROCESSING CONDITIONS

The Lewis acid catalyst is typically combined with the aprotic solventand charged to the reaction vessel under a nitrogen blanket. Thereaction vessel, as previously noted, is cooled to the desiredtemperature range typically from about -20° C. to about 40° C.,preferably about -5° C. to about 30° C., most preferably about 0° C. toabout 25° C.

The second aspect of the processing conditions of the present inventionis the preparation of a solution of the alpha-olefin monomer and thetertiary organo halide. The mixture of the tertiary organo halide andthe alpha-olefin is added incrementally to the stirred slurry of theLewis acid catalyst and the aprotic solvent.

The mixture within the reaction vessel is typically maintained at ±5° C.of the original desired temperature range. By controlling thetemperature of the reactants, it is possible to selectively obtain thealpha-olefin polymer mixture having the desired parameters. The reactionis typically conducted such that the polymerization is accomplished atfrom 0.1 to 5 hours, preferably 0.25 hours to about 3.5 hours.

After the polymerization is substantially complete, the catalyst systemmay be deactivated through the use of excess amounts of water ormethanol. The product is typically recovered by treating the reactionmixture with a drying agent such as magnesium sulfate followed byfiltration and solvent stripping to yield the neat liquid polymer.

QUANTITIES OF REACTANTS

The tertiary organo halide catalyst and the Lewis acid catalyst aretypically employed such that the final amount of each material presentin the reaction mixture on a molar basis is about 1.0:0.1 to about0.1:1.0, respectively. More preferably, the molar ratio of the catalystsis from about 5:1 to about 1:5, most preferably 2:1 to 1:2. It is notedthat the Lewis acid catalyst is described as being present in itsentirety in the initial phase of the reaction as described above. TheLewis acid catalyst may be added incrementally, however, the use of allof the catalyst at once is recommended.

The amount of the aprotic solvent, if any, utilized in relation to theLewis acid catalyst on a molar basis is typically about 100:1 to about1:1, more preferably about 75:1 to about 2:1, most preferably about 50:1to about 5:1.

The total alpha-olefin monomer charge to the Lewis acid catalyst istypically about 150:1 to about 10:1 preferably from about 75:1 to about20:1 on a weight basis. The suggested amounts of the alpha-olefinmonomer to the tertiary organo halide catalyst may thus be derived fromthe foregoing ratios.

THE PRODUCT

The products obtained herein typically contain a polymodal molecularweight distribution and are primary bimodal. The modal distribution ofthe polymers indicates that there are peak molecular weight maximums atmore than one point in the distribution of the molecular weight of thepolymer.

Typically, the molecular weight of the polymers obtained in the presentinvention will be from about 2,000 to about 100,000 (Mn). The peakmolecular weight maximums (Mn) in the bimodal distribution are typicallyat 2,000 to 5,000 for the lower molecular weight component and 50,000 to75,000 for the higher components. More preferably, the peak molecularweight maximums are from 3,500 to 4,500 and from 55,000 to 65,000. Theweight ratio of the lower molecular weight component to the highermolecular weight component is typically 95:5 to 70:30, and preferably90:10 to 80:20.

The molecular weight average and the number average molecular weight aredetermined as described below.

The number average molecular weight Mn, and the weight average molecularweight Mw are defined as follows.

The number average molecular weight is equal to the summation of thenumber of moles of each species times the molecular weight of eachspecies divided by the summation of the number of moles of each species.

The weight average molecular weight is equal to the summation of thenumber of moles of each species times the molecular weight of eachspecies squared divided by the summation of the number of moles of eachspecies times the molecular weight of each species.

Typically, the Mn and Mw values for polyalkenes for purposes of thisinvention, are determined by gel permeation chromatography (GPC). Thisseparation method involves column chromatography in which the stationaryphase is a heteroporus, solvent-swollen polymer network of a polystyrenegel varying in permeability over many orders of magnitude. As the liquidphase (tetrahydrofuran) containing the polymer sample passes through thegel, the polymer molecules diffuse into all parts of the gel notmechanically barred to them. The smaller molecules "permeate" morecompletely and spend more time in the column; the larger molecules"permeate" less and pass through the column more rapidly. The Mn and Mwvalues of the polymers can be obtained by one of ordinary skill in theart by the comparison of the distribution data obtained to a series ofcalibration standards of polymers of known molecular weightdistribution. For purposes of this invention, a series of fractionatedpolymers of isobutene, polyisobutene being the preferred embodiment, isused as the calibration standard.

For example, the Mw values disclosed herein are obtained using a WatersAssociates model 200 gel permeation chromatograph equipped with a 2.5 mlsyphon, a 2 ml sample injection lop and four stainless steel columns 7.8mm in diameter by 120 centimeters long. Each column was packed withSTYROGEL, a commercially available rigid, porous gel (in particle form)of crosslinked styrene/divinyl benzene copolymers. These gels areobtained from Waters Associates. The first column contains STYROGELhaving a retention volume of 10³ A. The second and third columns containSTYROGEL having a retention size of 500 A. The fourth column containsSTYROGEL having a retention volume of 60 A. The first column isconnected to the sample loop with stainless steel tubing, 83.3 cm long.The first column is connected to the second with a 2.3 cm length of thestainless steel tubing. The second and third columns are each connectedby 10.2 cm lengths of tubing. The fourth column is connected to thedetector by a 25.4 cm length of tubing. All the connecting tubing is 1.6mm in diameter.

Calibration standards were prepared by dialyzing a polyisobutylenesample having a specific gravity at 60° F. (15.5° C.) of 0.89 and aviscosity at 210° F. (99° C.) of 12.50 SUS. A sample of this polymer isfractionated by dialysis using a rubber membrane and a soxhletextraction apparatus with refluxing petroleum ether as solvent. Elevenfractions were taken; one sample each hour for the first seven hours,then three samples each four hours, and finally the residue which didnot permeate the membrane over a four hour period. The Mn of eachfraction was measured using vapor phase osmometry and benzene solvent.

Each calibration sample is then chromatographed. Approximately 7 mg ofsample is weighed into a small bottle which is then filled with 4 ml ofreagent grade tetrahydrofuran. The sealed bottle is stored overnightbefore analysis. The afore-described liquid phase chromatrograph isdegassed at 59° C. and a flow rate of 2.0 ml per minute oftetrahydrofuran maintained. Sample pressure is 180 psi (1280 KPa) andthe reference pressure 175 (1210 KPa) psi. The retention time of eachsample is measured. The Mw of each calibration sample is calculated fromthe Mn assuming the relationship 2 Mn=Mw. The retention times and Mw foreach sample, which are shown in the following table, were plotted toprovide a standardization curve. The Mn and Mw for sample polymers arethen obtained using this curve and the methods described in "Topics inChemical Instrumentation, Volumne XXIX, Gel Permeation Chromatography"by Jack Cages, published in The Journal of Chemical Education, Volume43, numbers 7 and 8. (1966).

Polyalkenes having the Mn and Mw calibrated values discussed above areknown in the art and can be prepared according to conventionalprocedures. Several such polyalkenes, especially polybutenes, arecommercially available.

    ______________________________________                                        RETENTION TIME VS. MOLECULAR WEIGHT                                           Rt*    Mw          Rt    Mw       Rt* Mw                                      ______________________________________                                        30     42240       40    638      50  229                                     31     26400       41    539      51  216                                     32     16985       42    453      52  202                                     33     10780       43    400      53  189                                     34     6710        44    361      54  178                                     35     4180        45    330      55  167                                     36     2640        46    304      56  156                                     37     1756        47    282                                                  38     1200        48    264                                                  39      865        49    246                                                  ______________________________________                                         *Rt = retention time in units of number of times syphon (2.5 ml) empties.     The syphon empties every 2.5 minutes.                                    

The products of the present invention are typically obtained as liquidmaterials at room temperature. The viscosity of the recovered productvaries from about 150 to about 1000 cSt at 100° C. Preferably theviscosity of the material at the same temperature is from about 200 toabout 400 cSt.

The following are suggested methods for preparing the polymers of thepresent invention.

EXAMPLE I

A 100 gallon (397 liter) reactor was equipped with a mechanical stirringsystem, monomer reservoir and feed inlet, thermometer, condenser,cooling jacket and N₂ atmosphere. A solution consisting of 69 kg1-octene, 69 kg 1-dodecene and 1.1 kg tertiary butyl chloride wascharged to the monomer feed reservoir. Water is present at about 0.25%weight of the total charge. To the stirred reactor was charged 89 kg drymethylene chloride and 3.45 kg anhydrous AlCl₃. This AlCl₃ slurry wascooled to 10° C., where upon a dropwise addition of theco-monomer/t-butyl chloride solution was initiated via the monomer feedinlet into the reactor over 3.5 hours. The polymerization temperaturewas maintained between 15°-20° C. After the co-monomer/t-butyl chloridecharge was complete, the polymerization mixture was stirred for anadditional 1.5 hours at 15°-20° C.

The polymerization mixture was warmed to room temperature with stirring.The AlCl₃ catalyst was neutralized by adding 28% aqueous NaOH solutioninto the product mixture with stirring at room temperature. Aftercatalyst neutralization, the aqueous and organic phases were separated.The organic phase was stripped of solvent at 150° C. and filtered togive a 92% yield of a liquid 1-olefin copolymer having a bulk viscosityat 100° C. of 240 cSt. Gel permeation chromatography (polyisobutylenestandard) indicates a copolymer Mn=4850, Mw=18800. A 20% wt. copolymertreatment of a 100N mineral oil gives a kinematic viscosity at 100° C.of 12.6 cSt.

EXAMPLE II

A five liter reactor was equipped with a stirrer, addition funnel,thermometer, condenser and a cooling bath. A solution of 1000 g (8.93moles) 1-octene, 1000 g (5.95 moles) 1-dodecene and 40.0 g (0.375 moles)tertiary amyl chloride was prepared and charged to the additionalfunnel. To the reactor was charged 1000 ml. dry methylene chloride and50.0 g anhydrous AlCl₃. A N₂ atmosphere was maintained throughout thepolymerization procedure. The stirred AlCl₃ slurry was cooled to 5° C.,whereupon a dropwise addition of the comonomer/t-butyl chloride solutionwas initiated and continued over 1.25 hours into the reactor. Thepolymerization temperature was maintained between 5°-10° C. After thecomonomer/t-butyl chloride charge was complete, the polymerizationmixture was stirred for an additional 1.5 hours at 5°-10° C.

The polymerization mixture was warmed to room temperature with stirring.The catalyst was neutralized by adding a water/MeOH solution dropwise.The product was then dried by Na₂ SO₄, filtered and the solvent removedto give a 90% yield of a liquid 1-olefin copolymer having a bulkviscosity at 100° C. of 250 cSt. Gel permeation chromatography(polyisobutylene standard) indicates an Mn=4000, Mw=25000. A treatmentof 20% wt. of this copolymer in a mineral oil blend gives a kinematicviscosity at 100° C. of 13.1 cSt.

EXAMPLE III

A five liter reaction vessel was equipped as in Example II. A solutionof 500 g (4.46 moles) 1-octene, 500 g (2.98 moles) 1-dodecene and 17.2 g(0.186 moles) tertiary butyl chloride was prepared and charged to theaddition funnel. To the reaction vessel was charged 500 ml. drymethylene chloride and 24.8 g (0.186 moles) anhydrous AlCl₃. An N₂atmosphere was maintained throughout the polymerization. The stirredAlCl₃ slurry was cooled to 15° C., whereupon a dropwise addition of thecomonomer/t-butyl chloride solution was initiated and continued over 2hours into the reactor. The polymerization temperature was maintainedbetween 15°-20° C. After the comonomer/t-butyl chloride charge wascomplete, the polymer mixture was stirred for an additional 1.5 hours at15°-20° C.

The polymer mixture was warmed to room temperature with stirring. Thecatalyst was deactivated by adding a stoichiometric excess of a H₂O/MeOH solution (based on the catalyst concentration) dropwise. Theneutralized polymer solution was then dried of H₂ O, filtered andsolvent evaporated to give a 90% yield of a liquid olefin copolymerhaving a bulk viscosity at 100° C. of 197 cSt. GPC analysis using apolyisobutylene standard, indicates a Mn=4000, Mw=16000. A treatment of20% wt. of this copolymer product in 100N mineral oil gives a kinematicviscosity of 12.0 cSt.

EXAMPLE IV

A 2 liter reaction vessel was equipped as in Example II. A solution of200 g (1.786 moles) 1-octene, 200 g (1.190 moles) 1-dodecene, 200 g(0.893 moles) 1-hexadecene and 9.0 g (0.097 moles) tertiary butylchloride was prepared and charged to the addition funnel. To thereaction vessel was charged 300 ml. dry methylene chloride and 12.9 ganhydrous AlCl₃. A N₂ atmosphere was maintained throughout thepolymerization. The stirred AlCl₃ slurry was cooled to 15° C., whereupona dropwise addition of the termonomer/t-butyl chloride solution wasinitiated and continued over two hours into the cooled AlCl₃ catalystslurry. The polymerization temperature was maintained between 15°-20° C.After the termonomer/t-butyl chloride charge was complete, the polymermixture was stirred for an additional 1.5 hours at 15°-20° C.

The polymerization mixture was warmed to room temperature with stirring.The catalyst was deactivated by adding a slight stoichiometric excess ofmethanol dropwise into the reactor. The neutralized polymer solution wasvacuum stripped of solvent, then filtered to give a 86% yield of aliquid 1-olefin permeation chromatography analysis using apolyisobutylene standard, indicates a Mn=3600, Mw=12000. for thisterpolymer system.

USAGE OF THE COMPOSITIONS

The shear stable viscosity improvers of the present invention areprimarily useful in gear lubricating formulations. Gear lubricatingformulations must provide a high degree of shear stability due to theintense mechanical action and close tolerances which the compositionmust endure during performance. Stated otherwise, shear stability is ameasure of the ability of the viscosity improver to maintain itsintegrity. The integrity of the viscosity improver is its abilitythroughout the lubricant's life to maintain viscosity of the lubricantcomposition under conditions of high temperature, and to not interferewith gear function at low temperatures.

The formulation of the compositions of the present invention into a gearoil or engine lubricant are typically accomplished by blending fromabout 1% to about 40%, preferably about 5% to about 25% by weight of theviscosity improver of the present invention into a base oil stock. Theproducts of the present invention may be combined into an oil productindirectly through the use of a diluent, e.g., a concentrate of theproduct, or by directly preparing the composition in combination with asuitable amount of an oil of lubricating viscosity. The oil oflubricating viscosity which is utilized in the preparation of the gearlubricants of the invention may be based on natural oils, syntheticoils, or mixtures thereof. Natural oils include animal oils andvegetable oils (e.g., castor oil, lard oil) as well as minerallubricating oils such as liquid petroleum oils and solvent-treated oracid-treated mineral lubricating oils of the paraffinic, naphthenic ormixed paraffinicnaphthenic types. Oils of lubricating viscosity derivedfrom coal or shale are also useful. Synthetic lubricating oils includehydrocarbon oils and halosubstituted hydrocarbon oils such aspolymerized and interpolymerized olefins (e.g., polybutylenes,polypropylenes, propyleneisobutylene copolymers, chlorinatedpolybutylenes, etc.); poly(1-hexenes), poly(1-octenes), poly(1-decenes),etc. and mixtures thereof; alkylbenzenes (e.g., dodecylbenzenes,tetradecylbenzenes, dinonylbenzenes, di-(2-ethylhexyl)-benzenes, etc.);polyphenyls (e.g., biphenyls, terphenyls, alkylated polyphenyls, etc.);alkylated diphenyl ethers and alkylated diphenyl sulfides and thederivatives, analogs and homologs thereof and the like.

Alkylene oxide polymers and interpolymers and derivatives thereof wherethe terminal hydroxyl groups have been modified by esterification,etherification, etc., constitute another class of known syntheticlubricating oils that can be used. These are exemplified by the oilsprepared through polymerization of ethylene oxide or propylene oxide,the alkyl and aryl ethers of these polyoxyalkylene polymers (e.g.,methylpolyisopropylene glycol ether having an average molecular weightof about 1000, diphenyl ether of polyethylene glycol having a molecularweight of about 500-1000, diethyl ether of polypropylene glycol having amolecular weight of about 1000-1500, etc.) or mono- and polycarboxylicesters thereof, for example, the acetic acid esters, mixed C₃ -C₈ fattyacid esters, or the C₁₃ oxo acid diester of tetraethylene glycol.

Another suitable class of synthetic lubricating oils that can be usedcomprises the esters of dicarboxylic acids (e.g., phthalic acid,succinic acid, alkyl succinic acids, alkenyl succinic acids, maleicacid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipicacid, linoleic acid dimer, malonic acid, alkyl malonic acids, alkenylmalonic acids, etc.) with a variety of alcohols (e.g., butyl alcohol,hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol,diethylene glycol monoether, propylene glycol, etc.) specific examplesof these esters include dibutyl adipate, di(2-ethylhexyl) sebacate,di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecylazelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, the2-ethylhexyl diester of linoleic acid dimer, the complex ester formed byreacting one mole of sebacic acid with two moles of tetraethylene glycoland two moles of 2-ethylhexanoic acid and the like.

Esters useful as synthetic oils also include those made from C₅ to C₁₂monocarboxylic acids and polyols and polyol ethers such as neopentylglycol, trimethylol propane, pentaerythritol, dipentaerythritol,tripentaerythritol, etc.

Silicon-based oils such as the polyalkyl-, polyaryl-, polyalkoxy-, orpolyaryloxy-siloxane oils and silicate oils comprise another usefulclass of synthetic lubricants (e.g., tetraethyl silicate, tetraisopropylsilicate, tetra-(2-ethylhexyl)silicate, tetra-(4-methyl-hexyl)silicate,tetra-(p-tert-butyl-phenyl)silicate,hexyl-(4-methyl-2-pentoxy)disiloxane, poly(methyl)siloxans,poly-(methylphenyl)siloxanes, etc.). Other synthetic lubri-cating oilsinclude liquid esters of phosphorus-containing acids (e.g., tricresylphosphate, trioxtyl phosphate, diethyl ester of decane phosphonic acid,etc.), polymeric tetrahydrofurans and the like.

Unrefined, refined and rerefined oils, either natural or synthetic (aswell as mixtures of two or more of any of these) of the type disclosedhereinabove can be used in the concentrates of the present invention.Unrefined oils are those obtained directly from a natural or syntheticsource without further purification treatment. For example, a shale oilobtained directly from retorting operations, a petroleum oil obtaineddirectly from primary distillation or ester oil obtained directly froman esterification process and used without further treatment would be anunrefined oil.

Refined oils are similar to the unrefined oils except they have beenfurther treated in one or more purification steps to improve one or moreproperties. Many such purification techniques are known to those skilledin the art such as solvent extraction, secondary distillation,hydrotreating, hydrocracking, acid or base extraction, filtration,percolation, etc.

Rerefined oils are obtained by processes similar to those used to obtainrefined oils which have been already used in service. Such rerefinedoils are also known as reclaimed or reprocessed oils and often areadditionally processed by techniques directed to removal of spentadditives and oil breakdown products.

Friction modifiers such as a fatty phosphite may be included in gearoils. The phosphites are generally of the formula (RO)₂ PHO. Thepreferred dialkylated phosphite as shown in the preceding formula istypically present with a mono-alkylated phosphite of the formula(RO)(HO)PHO. Both of these phosphites are concomitantly produced andthus mixture of the mono-phosphite and the di-phosphite is present.

In the above structure of the phosphite, the term "R" has been referredto as an alkyl group. It is, of course, possible that the alkyl isalkenyl and thus the terms "alkyl" and "alkylated", as used herein,embrace other than saturated alkyl groups within the phosphite. Thephosphite utilized herein is thus one having sufficient hydrocarbylgroups to render the phosphite substantially oleophilic and further thatthe hydrocarbyl groups are preferably substantially unbranched.

Other friction modifiers which are useful herein are borated fattyepoxides, borated glycerol monocarboxylates, and borated alkoxylatedfatty amines. Borated fatty epoxides are known from Canadian Pat. No.1,188,704 issued June 11, 1985 to Davis. The oil-solubleboron-containing compositions of Davis are prepared by reacting at atemperature from about 80° C. to about 250° C.

(A) at least one of boric acid or boron trioxide with

(B) at least one epoxide having the formula

    R.sup.1 R.sup.2 C[O]CR.sup.3 R.sup.4

wherein each of R¹, R², R³ and R⁴ is hydrogen or an aliphatic radical,or any two thereof together with the epoxy carbon atom or atoms to whichthey are attached, form a cyclic radical, said epoxide containing atleast 8 carbon atoms.

The borated amines are generally known from European publishedapplication Nos. 84 302 342.5 filed Apr. 5, 1984 and 84 307 355.2 filedOct. 25, 1984, both authored by Reed Walsh.

The borated amine friction modifiers are conveniently prepared by thereaction of a boron compound selected from the group consisting of boricacid, boron trioxide and boric acid esters of the formula B(OR)₃ whereinR is a hydrocarbon-based radical containing from 1 to about 8 carbonatoms and preferably from about 1 to about 4 carbon atoms with an amineselected from the group consisting of hydroxy containing tertiary. Theborated amines correspond to the formulae

    B--(OR.sup.1).sub.x NR.sup.2 R.sup.3                       (A)

    and

    B--[(OR.sup.1).sub.x Z].sub.3                              (B)

wherein Z is an imidazolene radical, R¹ in each formula is a loweralkylene based radical containing from 1 to about 8 carbon atoms, R² isa radical selected from the group consisting of hydrocarbon basedradicals containing from 1 to about 100 carbon atoms and alkoxy radicalsof the structure H(OR⁴)_(y) -- where R⁴ is a lower alkylene basedradical containing from 1 to about 8 carbon atoms, R³ and R⁵ (pendentfrom the ethylenic carbon in the 2 position in the imidazole (Z)radical) are each hydrocarbon based radicals containing from 1 to about100 carbon atoms, x and y are each an integer ranging from at least 1 toabout 50 and the sum of x+y is at most 75.

The borated fatty acid esters of glycerol are prepared by borating afatty acid ester of glycerol with boric acid with removal of the waterof reaction. Preferably, there is sufficient boron present such thateach boron will react with from 1.5 to 2.5 hydroxyl groups present inthe reaction mixture.

The reaction may be carried out at a temperature in the range of 60° C.to 135° C., in the absence or presence of any suitable organic solventsuch as methanol, benzene, xylenes, toluene, neutral oil and the like.

Fatty acid esters of glycerol can be prepared by a variety of methodswell known in the art. Many of these esters, such as glycerol monooleateand glycerol tallowate, are manufactured on a commercial scale. Theesters useful are oil-soluble and are preferably prepared from C₈ to C₂₂fatty acid or mixtures thereof such as are found in natural products.The fatty acid may be saturated or unsaturated. Certain compounds foundin acids from natural sources may include licanic acid which containsone keto group. Most preferred C₈ to C₂₂ fatty acids are those of theformula RCOOH wherein R is alkyl or alkenyl.

The fatty acid monoester of glycerol is preferred, however, mixtures ofmono- and diesters may be used. Preferably any mixture of mono- anddiester contains at least 40% of the monoester. Most preferably,mixtures of mono- and diesters of glycerol contain from 40 to 60 percentby weight of the monoester. For example, commercial glycerol monooleatecontains a mixture of from 45% to 55% by weight monoester and from 55%to 45% diester.

The amount of the friction modifier employed in the fluids of thepresent invention is typically from about 0.1% to about 5%, preferablyfrom about 0.25% to about 4%, and most preferably from about 0.5% toabout 3.5% by weight of the total composition.

A sulfurized olefin may be included in a lubricating product as anextreme pressure agent. Extreme pressure agents are materials whichretain their character and prevent metal to metal damage, e.g., contact,when gears are engaged and meshed. The sulfurization of olefins isgenerally known as is evidenced by U.S. Pat. No. 4,191,659 as previouslydisclosed.

The sulfurized olefins which are useful in the present invention arethose materials formed from olefins which have been reacted with sulfur.Thus, an olefin is defined as a compound having a double bond connectingtwo aliphatic carbon atoms. In its broadest sense, the olefin may bedefined by the formula R¹ R² C═CR³ R⁴, wherein each of R¹, R², R³ and R⁴is hydrogen or an organic radical. In general, the R values in the aboveformula which are not hydrogen may be satisfied by such groups as--C(R⁵)₃, --COOR⁵, --CON(R⁵)₂, --COON(R⁵)₄, --COOM, --CN,--C(R⁵)═C(R⁵)₂, --C(R⁵)═Y, --X, --YR⁵ or --Ar.

Each R⁵ is independently hydrogen, alkyl, alkenyl, aryl, substitutedalkyl, substituted alkenyl or substituted aryl, with the proviso thatany two R⁵ groups can be alkylene or substituted alkylene whereby a ringof up to about 12 carbon atoms is formed;

M is one equivalent of a metal cation (preferably Group I or II, e.g.,sodium, potassium, magnesium, barium, calcium);

X is halogen (e.g., chloro, bromo or iodo);

Y is oxygen or divalent sulfur; and

Ar is an aryl or substituted aryl radical of up to about 12 carbonatoms.

Any two of R¹, R², R³ and R⁴ may also together form an alkylene orsubstituted alkylene group; i.e., the olefinic compound may bealicyclic.

The sulfurized olefins useful in the present invention as extremepressure agents are typically utilized at from about 0.1% to about 5%,preferably from about 0.25% to about 4%, and most preferably from about0.5% to about 3.5% by weight of the total lubricant composition.

Additional ingredients which may be included in the products of thepresent invention are fatty acid amides which are useful as additionalfriction modifiers, particularly for reducing the static coefficient offriction. Further useful components herein include seal swell agentssuch as sulfones and sulfolanes. Suitable seal swell agents aredisclosed in Koch U.S. Pat. No. 4,029,587 issued June 14, 1977. A stillfurther useful component in the present invention is a foam suppressionagent such as a silicone oil. Any other typical ingredient may beincluded herein such as pour point depressants, dyes, odorants and thelike.

A further useful ingredient herein is a sulfurized lower olefin such asisobutylene. Such materials are described in U.S. Pat. No. 4,191,659issued to Davis on Mar. 4, 1980. The Davis materials may be added togear oils at levels of 0.1% to 10% by weight.

Additional useful ingredients which may be employed in the lubricant arethe following. These materials may be either combined directly into alubricant product or may be precombined with one or more ingredientssuch as the polymer of the present invention. Such additional materialsinclude, for example, detergents and dispersants of the ash-producing orashless type.

The ash-producing detergents are exemplified by oil-soluble neutral andbasic salts of alkali or alkaline earth metals with sulfonic acids,carboxylic acids, or organic phosphorus acids characterized by at leastone direct carbon-to-phosphorus linkage such as those prepared by thetreatment of an olefin polymer (e.g., polyisobutene having a molecularweight of 1000) with a phosphorizing agent such as phosphorustrichloride, phosphorus heptasulfide, phosphorus pentasulfide,phosphorus trichloride and sulfur, white phosphorus and a sulfur halide,or phosphorothioic chloride. The most commonly used salts of such acidsare those of sodium, potassium, lithium, calcium, magnesium, strontiumand barium.

The term "basic salt" is used to designate metal salts wherein the metalis present in stoichiometrically larger amounts than the organic acidradical. The commonly employed methods for preparing the basic saltsinvolve heating a mineral oil solution of an acid with a stoichiometricexcess of a metal neutralizing agent such as the metal oxide, hydroxide,carbonate, bicarbonate, or sulfide at at a temperature about 50° C. andfiltering the resulting mass.

Ashless detergents and dispersants are so called despite the fact that,depending on its constitution, the dispersant may upon combustion yielda non-volatile material such as boric oxide or phosphorus pentoxide;however, it does not ordinarily contain metal and therefore does notyield a metal-containing ash on combustion. Many types are known in theart, and any of them are suitable for use in the lubricant compositionsof this invention. The following are illustrative:

(1) Reaction products of carboxylic acids (or derivatives thereof)containing at least about 30 and preferably at least about 50 carbonatoms with nitrogen containing compounds such as amine, organic hydroxycompounds such as phenols and alcohols, and/or basic inorganicmaterials. Examples of these "carboxylic dispersants" are described inBritish Pat. No. 1,306,529 and in many U.S. patents including thefollowing:

    ______________________________________                                        U.S. Pat. No.                                                                             INVENTOR      ISSUE DATE                                          ______________________________________                                        3,163,603   Le Suer       December 29, 1964                                   3,184,474   Catto         May 18, 1965                                        3,215,707   Rense         November 2, 1965                                    3,219,666   Norman et al  November 23, 1965                                   3,271,310   Le Suer       September 6, 1966                                   3,272,746   Le Suer et al September 13, 1966                                  3,281,357   Vogel         October 25, 1966                                    3,306,908   Le Suer       February 28, 1967                                   3,311,558   Prizer et al  March 28, 1967                                      3,316,177   Dorer         April 25, 1967                                      3,340,281   Brannen       September 5, 1967                                   3,341,542   Le Suer et al September 12, 1967                                  3,346,493   Le Suer       October 10, 1967                                    3,351,552   Le Suer       November 7, 1967                                    3,381,022   Le Suer       April 30, 1968                                      3,399,141   Clemens       August 27, 1968                                     3,415,750   Anzenberger   December 10, 1968                                   3,433,744   Le Suer       March 18, 1969                                      3,444,170   Norman et al  May 13, 1969                                        3,448,048   Le Suer       June 3, 1969                                        3,448,049   Preuss et al  June 3, 1969                                        3,451,933   Leister       June 24, 1969                                       3,454,607   Le Suer       July 8, 1969                                        3,467,668   Gruber et al  September 16, 1969                                  3,501,405   Willette      March 17, 1970                                      3,522,179   Le Suer       July 28, 1970                                       3,541,012   Stuebe        November 17, 1970                                   3,542,680   Le Suer       November 24, 1970                                   3,543,678   Hobbs         December 1, 1970                                    3,567,637   Sabol         March 2, 1971                                       3,574,101   Murphy        April 6, 1971                                       3,576,743   Widmer et al  April 27, 1971                                      3,630,904   Musser et al  December 28, 1971                                   3,632,510   Le Suer       January 4, 1972                                     3,632,511   Chien-Wei Liao                                                                              January 4, 1972                                     3,697,428   Meinhardt     October 10, 1972                                    3,725,441   Murphy        April 3, 1973                                       4,234,435   Meinhardt     November 18, 1980                                   Re 26,433   Le Suer       August 6, 1968                                      ______________________________________                                    

(2) Reaction products of relatively high molecular weight aliphatic oralicyclic halides with amines, preferably polyalkylene polyamines. Thesemay be characterized as "amine dispersants" and examples thereof aredescribed for example, in the following U.S. patents:

    ______________________________________                                        U.S. Pat. No.                                                                            INVENTOR       ISSUE DATE                                          ______________________________________                                        3,275,554  Wagenaar et al September 27, 1966                                  3,438,757  Honnen et al   April 15, 1969                                      3,454,555  vander Voort et al                                                                           July 8, 1969                                        3,565,804  Honnen et al   February 23, 1971                                   ______________________________________                                    

(3) Reaction products of alkyl phenols in which the alkyl group containsat least about 30 carbon atoms with aldehydes (especially formaldehyde)and amines (especially polyalkylene polyamines), which may becharacterized as "Mannich dispersants". The materials described in thefollowing U.S. patents are illustrative:

    ______________________________________                                        U.S. Pat. No.                                                                             INVENTOR      ISSUE DATE                                          ______________________________________                                        2,459,112   Oberright     January 11, 1949                                    2,962,442   Andress       November 29, 1960                                   2,984,550   Chamot        May 16, 1961                                        3,036,003   Verdol        May 27, 1962                                        3,166,516   Kirkpatrick et al                                                                           January 19, 1965                                    3,236,770   Matson        February 22, 1966                                   3,355,270   Amick         November 28, 1967                                   3,368,972   Otto          February 13, 1968                                   3,413,347   Worrel        November 26, 1968                                   3,442,808   Traise        May 6, 1969                                         3,448,047   Traise        June 3, 1969                                        3,454,497   Wittner       July 8, 1969                                        3,459,661   Schlobohm     August 5, 1969                                      3,461,172   Previc        August 12, 1969                                     3,493,520   Verdol et al  February 3, 1970                                    3,539,633   Piasek et al  November 10, 1970                                   3,558,743   Verdol et al  January 26, 1971                                    3,586,629   Otto et al    June 22, 1971                                       3,591,598   Traise et al  July 6, 1971                                        3,600,372   Udelhofen et al                                                                             August 17, 1971                                     3,634,515   Piasek et al  January 11, 1972                                    3,649,229   Otto          March 14, 1972                                      3,697,574   Piasek et al  October 10, 1972                                    3,725,277   Worrel        April 3, 1973                                       3,725,480   Traise et al  April 3, 1973                                       3,726,882   Traise et al  April 10, 1973                                      3,980,569   Pindar et al  September 14, 1976                                  ______________________________________                                    

(4) Products obtained by post-treating the carboxylic, amine or Mannichdispersants with such reagents as urea, thiourea, carbon disulfide,aldehydes, ketones, carboxylic acids, hydrocarbon-substituted succinicanhydrides, nitriles, epoxides, boron compounds, phosphorus compounds orthe like. Exemplary materials of this kind are described in thefollowing U.S. patents:

    ______________________________________                                        U.S. Pat. No.                                                                            INVENTOR       ISSUE DATE                                          ______________________________________                                        3,036,003  Verdol         May 22, 1962                                        3,087,936  Le Suer        April 30, 1963                                      3,200,107  Le Suer        August 10, 1965                                     3,216,936  Le Suer        November 9, 1965                                    3,254,025  Le Suer        May 31, 1966                                        3,256,185  Le Suer        June 14, 1966                                       3,278,550  Norman et al   October 11, 1966                                    3,280,234  Osborn         October 18, 1966                                    3,281,428  le Suer        October 25, 1966                                    3,282,955  Le Suer        November 1, 1966                                    3,312,619  Dale           April 4, 1967                                       3,366,569  Norman et al   January 30, 1968                                    3,367,943  Miller et al   February 6, 1968                                    3,373,111  Le Suer et al  March 12, 1968                                      3,403,102  Le Suer        September 24, 1968                                  3,442,808  Traise et al   May 6, 1969                                         3,455,831  Davis          July 15, 1969                                       3,455,832  Davis          July 15, 1969                                       3,493,520  Verdol et al   February 3, 1970                                    3,502,677  Le Suer        March 24, 1970                                      3,513,093  Le Suer        May 19, 1970                                        3,533,945  Vogel          October 13, 1970                                    3,539,633  Piasek et al   November 10, 1970                                   3,573,010  Mehmedbasich   March 30, 1971                                      3,579,450  Le Suer        May 18, 1971                                        3,591,598  Traise         July 6, 1971                                        3,600,372  Udelhofen      August 17, 1971                                     3,639,242  Le Suer        February 1, 1972                                    3,649,229  Otto           March 14, 1972                                      3,649,659  Otto et al     March 14, 1972                                      3,658,836  Vineyard       April 25, 1972                                      3,697,574  Piasek et al   October 10, 1972                                    3,702,757  Mehmedbasich et al                                                                           November 14, 1972                                   3,703,536  Piasek et al   November 21, 1972                                   3,704,308  Piasek et al   November 28, 1972                                   3,708,422  Swanson        January 2, 1973                                     ______________________________________                                    

(5) Interpolymers of oil-solubilizing monomers such as decylmethacrylate, vinyl decyl ether and high molecular weight olefins withmonomers containing polar substituents, e.g., aminoalkyl acrylates oracrylamides and poly-(oxyethylene)-substituted acrylates. These may becharacterized as "polymeric dispersants" and examples thereof aredisclosed in the following U.S. patents:

    ______________________________________                                        U.S. Pat. No.                                                                             INVENTOR     ISSUE DATE                                           ______________________________________                                        3,329,658   Fields       July 4, 1967                                         3,449,250   Fields       June 10, 1969                                        3,519,565   Coleman      July 7, 1970                                         3,666,730   Coleman      May 30, 1972                                         3,687,849   Abbott       August 29, 1972                                      3,702,300   Coleman      November 7, 1972                                     ______________________________________                                    

The term "minor amount" as used in the specification and appended claimsis intended to mean that when a composition contains a "minor amount" ofa specific material that amount is less than about 50% by weight of thecomposition.

The term "major amount" as used in the specification and appended claimsis intended to mean that when a composition contains a "major amount" ofa specific material that amount is more than about 50% by weight of thecomposition. In relation to one another, a major amount of one componentmeans that component is present in a greater amount than the componentwhich is present in a minor amount.

A further desirable utility of the polymers of the present invention isin a hydraulic fluid. Typical ingredients in a hydraulic fluid includeany or all of the above components useful in a lubricating oil.

A further feature of the present invention is the incorporation of about0.1% to about 25%, preferably about 0.5% to about 20% by weight of theviscosity improver of the present invention in a grease. Greases aretypically lithium, calcium or magnesium based fatty acids, inparticular, the stearates.

The following are compositions prepared using the polymers of thepresent invention:

EXAMPLE V

An all mineral oil based SAE 75W90 gear oil was prepared consisting of66.62% wt. mineral oil+10% wt. Anglamol 6043^(a)) +0.5% pour pointdepressant+22.9% wt. of the copolymer composition of Example I. Thekinematic viscosity at 100° C. of this fully formulated, all mineral oilbased multigrade gear oil lubricant was 14.1 cSt. ASTM D2983 viscosity(Brookfield at -40° C.) of this lubricant blend was 134,000 cPs.

EXAMPLE VI

An all mineral based SAE 90 gear lubricant was formulated with 73% wt.100N mineral oil+1% wt. pour point depressant+4% wt. Anglamol 99^(b))additive+22% wt. of the copolymer composition of Example I. Thekinematic viscosity at 100° C. of this blend was 14.5 cSt. Shear testingof this formulation was conducted using the Nieman (FZG) Four-SquareGear test rig. The conditions used were a stage 5 loading at 90° C. and2900 RPM for 19 hours. The viscosities of the test formulation weredetermined before and after the procedure. The observed viscosity losswas less than 10%.

(a) Anglamol^(R) 6043: is a conventional S/P gear oil performanceadditive

(b) Anglamol^(R) 99 is a conventional S/P gear oil performance additive

What is claimed is:
 1. A liquid alpha-olefin polymer composition havinga polymodal distribution with peak molecular weight maximums at 2,000 to5,000 and at 50,000 to 75,000.
 2. The liquid alpha-olefin polymer ofclaim 1 is obtained from an alpha-olefin of 4 to about 30 carbon atomsand mixtures thereof.
 3. The liquid alpha-olefin polymer of claim 1wherein the polymodal distribution is bimodal.
 4. The liquidalpha-olefin polymer of claim 1 obtained from an alpha-olefin of 6 toabout 16 carbon atoms.
 5. The liquid alpha-olefin polymer of claim 1wherein the peak molecular weight maximums are 3,500 to 4,500 and 55,000to 65,000.
 6. A lubricating oil, functional fluid or grease containingthe liquid alpha-olefin polymer of claim 1.